Process and means for preventing one of two centriftjgally-separated



May .6 1924.

H. o. LINDGREN PROCESS AND MEANS FOR PREVENTING ONE OF TWO CENTRIFQ ALLY SEPARATBD LIQUIDS FROM CONTAMINATIXiG THE! OTHER Filed Nova 14. 1925 Patented May 6, 1924.

UNITED STATES 1,493,206 PATENT OFFICE.

HANS OLOF LINDGREN, OF STOCKHOLM, SWEDEN, ASSIGNOR TO THE DE LAVAL SEPARATOR COMPANY, OF Y ORK, N. Y., A CORPORATION OF NEW JERSEY.

PROCESS AND MEANS FOR PREVENTING ONE OF TWO GENTRIFUGALLY-SEPARATED LIQUIDS FROM CONTAMINATING THE OTHER.

Application filed November 14, 1923.

To all whom it may concern.

Be it known that I, HANS OLOF LINDGREN,

a subject of the King ofvSweden, residing at Stockholm, Sweden, have invented a new and useful Improvement in Processes and Means for Preventing One of Two Centrifugally-Separated Liquids from Contaminating the Other, of which the follow ing is a full, clear, and exact description, reference being had to the accompanying drawings, which form a part of this specification.

In the centrifugal separation of a liquid from a contaminating liquid of different specific gravity, whether or not they are admixed with solid impurities, it is possible, with the most nearly perfected type of centrifuge, to effect a practically complete separation within the bowl of the liquid that it is desired to recover in a pure condition and to discharge the liquid in that condition from the bowl outlet. 'Heavy solid impurities will be retained on the inner wall of the bowl until the separating operation is finished, but it is nearly always desirable to provide the bowl with a separate outlet for the continuous discharge of the contaminating liquid, and this is always imperative if the total volume of mixed liquid is large or if the contaminating liquid is present in a considerable proportion. During the dis charge of the two liquids from their respective outlets, the difficulty arises that there is a tendency for a small proportion of the contaminating liquid to remix with the other liquid. This tendency will be more readily understood by explaining, in general, the construction of a typical bowl and its receiving pans. It will be assumed, in this explanation, that it is sought to de hydate transformer oil or switch oil, which are examples of liquids which must be puritied to an almost absolute degree and which, therefore, cannot be successfully treated by the centrifugal separation process if there is any appreciable remixing of water with oil during the discharge of the two liquids.

A typical two-outlet centrifugal bowl has its heavier liquid discharge outlet (in the case assumed, the water outlet) near the top of thebowl just below its neck and relatively distant from the axis of rotation. The lighter liquid discharge outlet (in the case assumed, the oil outlet) is located in the Serial No. 674,765.

neck of the bowl above the water outlet and relatively near the axis of rotation. There is usually a third, or overflow, outlet at the top of the neck of the bowl. Surrounding the upper part and neck of the bowl are a corresponding number of covers or receiving pans or receptacles. In the construction assumed, there would therefore be three receptacles: a lower one for the water, a middle one for the oil and an upper one to receive any overflow in case the bowl should become loaded beyond its capacity. The pans, which are stationary, are necessarily provided with central orifices of greater diameter than the parts of the bowl that they respectively surround, leaving an annular space between the bowl and each pan.

Assuming that the bowl is functioning efiiciently, when the oil discharges from the bowl and streams, across the annular space mentioned, into the oil receptacle, it is practically free from water. A short distance below the oil discharge, water is simultaneously streaming .into the water receptacle. It is clear that if even a very small proportion of water in this discharging stream mixes with the dischargingstream of oil, the oil will not pass into the oil receptacle in a completely dehydrated condition. This remixing does actually occur. The explanation of thephenomenon is that the water is discharged in finely divided drops or particles which remain suspended in the air and also that the air itself becomes saturated with dissolved moisture.

Means have been devised with the object in view of preventing fine drops of water suspended in the air from getting into the oil receptacle, and certain of such means have been fairly effective. It may be questioned, however, whether such means ever prevent the finest water particles from being carried by the air whirls into the oil stream; and it is certain that such means do not prevent moisture dissolved in the air from rising to'the discharging'oil stream and :there being caught by the discharging oil, especially as-the latter is partly in the form of a very fine spray.

The present invention is designed to effectually prevent any water, either in the form of drops or particles or in the form of dissolved moisture, that maybe taken up by air currents, from being carried into the oil receptacle or into the stream of oil discharging from the bowl into the receptacle. This is accomplished by creating a draft of air moving first through the zone of discharging oil and then through and past the zone of discharging Water so that while some oil mist may be carried into the water zone there can be no reverse movement that would carry water, in any form, into the oil zone. Specific means for creating and maintaining this draft of air are herein disclosed and embody decidedly preferential means for accomplishing the result sought and it is the intention to claim such means broadly and specifically; although it will be understood that the successful operation of the process is not clependent upon the employment-of any particular means.

Fig. 1 of the drawings is a vertical section illustrating a centrifugal bowl, its hous ing, the receiving pans and means for creating the described draft of air.

Fig. 2 is a partial vertical section showing alternative means for the same purpose.

The centrifugal bowl a is supported and rotated in any known way and is provided withthe usual surrounding housing 6. At any point or are of the circumference c is the discharge for water. The oil discharges at any point or are of the circumference d. The overflow discharge, if such be provided, is indicated at 6. Four stationary pans and covers are provided, each oneof which except the lowest forms the top or cover of one receptacle and each one of which except the highest forms the bottom of one receptacle; thereby forming three receptacles, one, f, for water, another, 9, for oil, and a third, h, for overflow. The receptacles are provided respectively with the discharge spouts 2', j and 70. The above de scribed construction and arrangement are old and customary.

At or near the periphery of the housing I) is an opening m, the size of which can be regulated, if desirable or necessary, by means of an adjustable valve n. The water spout i and the overflow spout k are either of more restricted cross-sectional dimensions than the oil spout j ,(e. g, spout k) or they are provided with adjustable throttle valves (e. 'g., valve 0 in spout i and valve 79 in spout is), so that the passage of air through the oil spout may be more unrestricted and capacious than the passages through the other spouts. The bowl a may be provided with exterior Wings 1", which, as shown, are located on the cylindrical part of the bowl so that, in the latters rotation, the circumf erential current of air created by the rotation of the bowl, will be substantially strengthened. The use of these wings is, however,, optional, and their form or location need not be as shown, so long as, if

used at all, they are so positioned as to create, or assist in creating, a draft of air from the zone of discharging or discharged oil to and past the zone of discharging or discharged water.

In the particular embodiment of the invention shown and described, when the bowl is in rotation, the air enclosed between the bowl and its housing is put into rotation, thereby creating a centrifugal force that drives the air out through. the opening m. Air, flows then through the collecting vessels so as to come in through the pipes and down through the central openings of the pans. By suitably regulating the opening through on and the capacity of the pipes, as described, a predominatingly strong air current may be sucked in through the oil pipe j andoil receptacle 9. Therebya strong current of air occurs around the bowl neck past the annular opening around the oil discharge down to and past the annular opening around the water discharge. This air current can be maintained so strong that no secondary whirls will be produced capable of carrying water drops or moisture in any form from the water zone into the .oil zone; and consequently no remixing with the oil of any portion of the water that'has been separated therefrom within the bowl can occur.

If an air discharge opening be provided in the housing it is not necessary that it be .placed in the particular location shown in Fig. 1. For example, an opening 8 may be placed in the bottom of the housing relatively near the axis of rotation. This opening may be provided with a throttling valve 25;

and wings, such as a, of any suitable shape may be so positioned between the bowl periphery and the opening 8, with or with,- out a partition wall 2) dividing the part of the housing containing the wings from the remainder of the housing, so that between the wings the air will not participate, or at least not fully participate, in the rotation of the surrounding air and centripetal air currents will form that will conduct the air from the space around the bowl to the opening 8.

Having now fully described my invention, what I claim and desire to protect by Letters Patent is:

1. In the art of eli inating from a liquid of relatively low specific gravity a contaminating liquid of relatively high specific gravity which is present in relatively small proportion in the liquid to be purified, the process of preventing the contaminating iquid from remixing with the liquid to be urifiled in the discharge of the two liquids rom the locus of separation to their ultimate points of delivery, which com rises discharging the contaminating liqui below the level of the discharging purified liquid, directing the rotating column of air created by the rotation of the bowl away from the bowl at a level substantially below the loci of discharge of the two liquids, creating suctional currents of air along the paths of both discharging liquids in the reverse direction to the flow of the liquids, one of said currents flowing down past the loci of discharge of both liquids and the other current flowing down past the locus of discharge of only the contaminating liquid, and restricting the flow of the current of air along the path of the discharging contaminating liquid relative to the flow of the current of air along the path of the discharging purified liquid.

2. In the art of eliminating from a liquid of relatively low specific gravity a contaminating liquid of relatively high specific gravity which is present in relatively small proportion in the liquid to be purified, the process of preventing the contaminating liquid from re-mixing with the liquid to be purified in the discharge of the two liquids from the locus of separation to their ultimate points of delivery, which comprises discharging the contaminating liquid below the level of the discharging purified liquid, and establishing a relatively restricted flow of air along the path, and reversely to the direction of flow, of the discharging contaminated liquid and downwardly past the locus of discharge of said contaminating liquid, and establishing a relatively strong flow of air along the path, and reversely to the direction of flow, of the discharging purified liquid and downwardly past the loci of discharge of both liquids.

3. In centrifuges for separating liquids of different specific gravities to prevent the contamination of one liquid by the other in the discharge of the two liquids from the bowl to their ultimate points of delivery, the combination with a rotary bowl provided with discharges for the respective liquids, the discharge from the bowl for the liquid to be maintained uncontaminated being above the discharge from the bowl for the other liquid, receptacles, one above the other, for receiving the respectively discharging liquids, and a housing around the bowl provided with an opening for escape of air, of means within the housing and exterior of the bowl adapted to substantially augment the downward draft of air past said discharges into the housing and out said opening.

4. In centrifuges for separating liquids of different specific gravities to prevent the contamination of one liquid by the other in the discharge of the two liquids from the bowl to their ultimate points of delivery, the combination of a rotary bowl provided with discharges for the respective liquids, the discharge from the bowl for the liquid to be maintained uncontaminated being above the discharge from the bowl for the other liquid, receptacles, one above the other, for receiving the respectively discharging liquids, there being means below said discharges creating a draft of air downwardly past said discharges, thereby creating a flow of air through said receptacles in a direction reverse to the flow of the liquids therein, and means providing asub'stantially larger volume of air fiow along the path of flow of the discharging purified liquid than along the path of flow of the discharging contaminating liquid.

In testimony of which invention, I have hereunto set my hand, at Stockholm, Sweden, on this 27th day of October, 1923.

HANS OLOF LINDGREN. 

